This invention relates to energy conservation and has particular relationship to the use of solar cells in energy conservation. In the typical use of solar cells a fluid, usually a liquid such as water, is circulated through an array of tubes. The tubes are composed of highly thermally conducting material, such as copper, and are coated with material which is highly radiation absorptive. The tubes are disposed, usually on the roof of a building, for example, a dwelling, so that they are subject to the radiation from the sun. The fluid in the tubes is heated by this radiation and it is circulated to a fluid reservoir whence the fluid is drawn when required.
It is an object of this invention to maximize the energy which is conserved by solar heating systems.